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led.c

/*
 * arch/sh64/kernel/led.c
 *
 * Copyright (C) 2002 Stuart Menefy <stuart.menefy@st.com>
 *
 * May be copied or modified under the terms of the GNU General Public
 * License.  See linux/COPYING for more information.
 *
 * Flash the LEDs
 */
#include <linux/stddef.h>
#include <linux/sched.h>

void mach_led(int pos, int val);

/* acts like an actual heart beat -- ie thump-thump-pause... */
void heartbeat(void)
{
      static unsigned int cnt = 0, period = 0, dist = 0;

      if (cnt == 0 || cnt == dist) {
            mach_led(-1, 1);
      } else if (cnt == 7 || cnt == dist + 7) {
            mach_led(-1, 0);
      }

      if (++cnt > period) {
            cnt = 0;

            /*
             * The hyperbolic function below modifies the heartbeat period
             * length in dependency of the current (5min) load. It goes
             * through the points f(0)=126, f(1)=86, f(5)=51, f(inf)->30.
             */
            period = ((672 << FSHIFT) / (5 * avenrun[0] +
                                  (7 << FSHIFT))) + 30;
            dist = period / 4;
      }
}


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